TAMM STATES OF CARBON NANOTUBES

The fine structure of the pi-electron spectrum of semi-infinite carbot ubulenes (cylindrical graphene tubes) is investigated. Together with c losed short-diameter tubelenes, open nanotubes whose terminal fragment s contain heteroatoms are studied. Algebraic equations are obtained fo r the one-electron energy levels corresponding to wave functions local ized on a terminal fragment. It is shown that Tamm energy levels, lyin g in either the band gaps or the continuous spectrum (resonance states ), can exist in the systems studied. (C) 1996 American Institute of Ph ysics.